The present invention relates to an agent for contact lenses. More particularly, the present invention relates to an agent for contact lenses, which contains an oxo-acid compound and/or a polyacid compound.
In recent years, various kinds of contact lenses, such as hard contact lens, oxygen permeable hard contact lens, soft contact lens and the like, have been widely used. These contact lenses easily become unclean due to the components contained in lacrimal fluid, such as protein, and require daily cleaning, sterilization and preservation.
The stain (e.g., protein) attached to the surface of a contact lens can be decomposed and removed by protease, and many cleaning agents have been proposed. For example, an agent in a solid form, which mainly contains a protease, such as tablet, granule, powder and the like, is supplied and an end user dissolves the agent each time in purified water and the like before use. This method requires dissolution of protease in a solid state every time the agent is used. As a result, the end user is forced to suffer from high cost and complicated handling.
In an attempt to solve such problems, some agents providing a protease in a solution state have been proposed as treating agents for contact lenses (JP-A-60-196722, JP-B-7-66113, JP-A-4-51015 and the like). In addition, a protein remover containing urea or a guanidine acid salt and specific reducing agent (JP-A-52-56852), a protein remover containing an aqueous alkali salt of hypobromous acid containing a specific amount of a compound such as citric acid and the like (JP-A-59-45339), a cleaning agent containing anionic surfactant such as alkylbenzenesulfonate and the like and a reducing agent such as sulfite and the like (JP-A-60-254114), a cleaning agent containing thiourea and surfactant and/or reducing agent (JP-A-61-51121) and the like have been proposed.
However, these protein removers and cleaning agents cause strong irritation to cornea, and require thorough rinsing with water after protein removal.
Further, a method has been proposed, which utilizes an electric field afforded to a lens to migrate stain deposit, thereby to clean and sterilize the contact lens (Japanese Patent Application under PCT laid-open under kohyo No. 9-511340).
This method requires previous application of an electric field to the contact lens, and also requires a special washing device.
Therefore, there is a demand on an agent for contact lenses which can remove protein irrespective of the kind of contact lens and without using a specific washing device, and which requires no water washing after protein removal.
The present inventors have conducted intensive studies in an attempt to achieve the above-mentioned objects and found that use of an oxo-acid compound and/or a polyacid compound as a protein remover enables removal of protein irrespective of the kind of contact lens and without using a specific washing device, and obviates water washing after protein removal, which resulted in the completion of the present invention.
Accordingly, the present invention provides the following.
(1) An agent for contact lenses comprising an oxo-acid compound and/or a polyacid compound as an active ingredient.
(2) The agent for contact lenses of (1), wherein the oxo-acid compound is an oxo-acid or a salt thereof or a hydrate thereof.
(3) The agent for contact lenses of (1), wherein the polyacid compound is a polyacid or a salt thereof or a hydrate thereof.
(4) The agent for contact lenses of (1) or (2), wherein the oxo-acid compound is an oxo-acid compound of a transition metal, typical metal or metalloid.
(5) The agent for contact lenses of (4), wherein the transition metal is vanadium, chromium, molybdenum or tungsten.
(6) The agent for contact lenses of (4), wherein the typical metal is tin.
(7) The agent for contact lenses of (4), wherein the metalloid is silicon or tellurium.
(8) The agent for contact lenses of (1) or (3), wherein the polyacid compound contains at least tungstic acid.
(9) The agent for contact lenses of any of (1) to (8), wherein the agent is a protein remover for contact lenses.
(10) The agent for contact lenses of any of (1) to (9), wherein the oxo-acid compound and/or the polyacid compound are/is contained in a proportion of 0.001-2.0 (W/V)%.
In the present specification, by the oxo-acid compound is meant an oxo-acid or a salt thereof or a hydrate thereof.
The center atom of the oxo-acid compound to be contained in the agent for contact lenses of the present invention is exemplified by transition metals, typical metals and metalloids.
Examples of the transition metal include the elements of groups 3 to 11 of the periodic table, preferably the elements of groups 5 and 6, such as vanadium (V), chromium (Cr), molybdenum (Mo), tungsten (W) and the like.
The typical metal is exemplified by the typical metals of groups 13 and 14 of the periodic table, preferably tin (Sn) and the like.
The metalloid is an element having the properties between a metal and a nonmetal. Examples thereof include silicon (Si), germanium (Ge), selenium (Se), antimony (Sb), tellurium (Te) and the like. Preferable metalloid includes silicon (Si), tellurium (Te) and the like.
Preferable oxo-acid includes vanadic acid (HVO3), chromic acid (H2CrO4), molybdic acid (H2MoO4), tungstic acid (H2WO4), stannic acid (H2SnO3), silicic acid (H2SiO3), telluric acid (H2TeO4) and the like.
The oxo-acid that can be used for the agent for contact lenses of the present invention may be in the form of a salt with alkali metal (e.g., sodium, potassium and the like) or alkaline earth metal (e.g., magnesium, calcium and the like). The oxo-acid or a salt thereof may be a hydrate containing water of crystallization.
The polyacid compound to be contained in the agent for contact lenses of the present invention may be an isopolyacid compound or a heteropolyacid compound. The isopolyacid means a polyacid having a polynuclear structure wherein a single oxo-acid has been condensed. The heteropolyacid means a polyacid having a polynuclear structure wherein two or more kinds of oxo-acids have been condensed. The heteropolyacid has a structure comprising a condensed structure of an acid forming the skeleton (skeleton acid) and a small number of other kinds of atoms (hetero atom) contained in the center thereof and the like.
As used in this specification, xe2x80x9cpolyacid compoundxe2x80x9d refers to a polyacid or a salt thereof or a hydrate thereof.
The isopolyacid compound to be used in the present invention may be, for example, a condensed product of oxygen acid of an element, such as sulfur (S), silicon (Si), phosphorus (P), boron (B), a transition element belonging to the group 5 (vanadium (V), niobium (Nb), tantalum (Ta) and the like), a transition element belonging to the group 6 (chromium (Cr), molybdenum (Mo), tungsten (W) and the like) and the like. Preferably, it is a condensed product of oxygen acid of an element, such as vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W) and the like. Specific examples thereof include heptaoxodisulfuric acid, pentaoxodisulfuric acid, disilicic acid, trisilicic acid, tetrasilicic acid, diphosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, tetraboric acid, pentaboric acid, hexavanadic acid, decavanadic acid, hexaniobic acid, dichromic acid, trichromic acid, tetrachromic acid, dimolybdic acid, hexamolybdic acid, heptamolybdic acid, octamolybdic acid, decamolybdic acid, dodecamolybdic acid, hexatungstic acid, decatungstic acid, paratungstic acid, metatungstic acid and the like. These isopolyacids may be a chain or a ring. When used in the form of a salt with alkali metal (e.g., sodium, potassium and the like) or alkaline earth metal (e.g., magnesium, calcium and the like), these isopolyacids become stable, and therefore, preferable. Examples of preferable salts of isopolyacid include sodium decavanadate, sodium decatungstate and the like. The isopolyacid or a salt thereof may be a hydrate containing water of crystallization.
The center atom of the skeleton acid of the heteropolyacid to be used for the present invention is an element such as vanadium (V), niobium (Nb), tantalum (Ta), molybdenum(Mo), tungsten (W) and the like, as in the case with isopolyacid, wherein hetero atom is not limited to a metal atom and includes an element such as phosphorus (P), silicon (Si), boron (B), germanium (Ge) and the like. The center atom of the skeleton acid may consist of one or more kinds of atoms.
The ratio of the number of the center atom of the hetero atom to that of the skeleton acid of the heteropolyacid is not particularly limited as long as they can form a polyacid having the above-mentioned polynuclear structure. It is preferably 1:6, 1:9, 1:12, 2:18 and the like.
Examples of heteropolyacid to be used in the present invention include those having one kind of the center atom of the skeleton acid, such as heteropolymolybdic acid, heteropolytungstic acid and the like, and those having two kinds of the center atoms of the skeleton acid, such as heteropolyvanadomolybdic acid, heteropolyvanadotungstic acid and the like.
Examples of heteropolymolybdic acid include H4(SiMo12O40), H4(GeMo12O40), H3(PMo12O40), H8(SiMo11O39), H8(GeMo11O39), H7(PMo11O39), H3(PMo12O40), H6(P2Mo18O62), H6(P2Mo5O23) and the like.
Examples of heteropolytungstic acid include H5(BW12O40), H4(SiW12O40), H4(GeW12O40), H3(PW12O40), H9(BW11O39), H8(SiW11O39), H8(GeW11O39), H7(PW11O39), H6(P2W18O62), H10(P2W17O61), H6(P2W5O23), H21(P4W8O40) and the like.
Examples of heteropolyvanadomolybdic acid include H4(PMo11VO40), H5(PMo10V2O40), H6(SiMo10V2O40), H6(PMo9V3O40) and the like. Examples of heteropolyvanadotungstic acid include H4(PW11VO40), H5(SiW11VO40), H5(PW10V2O40), H6(SiW10V2O40), H7(PW9V3O40), H5(PW10V2O40), H6(PW6V3O31), H7(SiW9V3O40) and the like.
The heteropolyacid that can be used in the present invention may be a salt with alkali metal (e.g., sodium, potassium and the like) or alkaline earth metal (e.g., magnesium, calcium and the like). It is preferably a salt in view of stability. Examples of preferable salt of heteropolyacid include Na8(GeW11O39), Na5(PW10V2O40) and the like. The heteropolyacid or a salt thereof may be a hydrate containing water of crystallization.
The above-mentioned oxo-acid compound and/or polyacid compound can be used alone or in combination.
The agent for contact lenses of the present invention contains an oxo-acid compound and/or a polyacid compound in a proportion of 0.001-2.0 (W/V) %, preferably 0.01-1.0 (W/V) %. When the content is less than 0.001 (W/V) %, a sufficient protein removal effect cannot be achieved.
The agent for contact lenses of the present invention can be used for cleaning, protein removal, sterilization, preservation and the like of contact lenses. The agent can be used for respective uses for contact lenses, and further as a single agent for contact lenses for both cleaning and protein removal, and additionally for sterilization and/or preservation.
The agent for contact lenses of the present invention can contain other antimicrobial agent, buffer, isotonicity agent, surfactant, chelating agent, thickener, wetting agent and detergency improver as long as they do not act adversely to the object of the present invention.
Examples of antimicrobial agent include benzalkonium chloride, chlorhexidine gluconate, sorbic acid, a salt thereof, thimerosal, chlorobutanol, phenethyl alcohol, p-hydroxybenzoates and the like, which are selected according to the type of each contact lens, whether hard contact lens, oxygen permeable hard contact lens or soft contact lens, as long as they do not act adversely to the object of the present invention.
A buffer is used to make the pH of the agent for contact lenses of the present invention approximately 4-10, preferably 5-8. As a buffer, an acid and a salt thereof, or a base and a salt thereof, are combined by a conventional method to achieve a desired pH. Examples of the buffer include boric acid, sodium borate, citric acid, sodium citrate, tartaric acid, sodium tartrate, gluconic acid, sodium gluconate, acetic acid, sodium acetate, phosphoric acid, sodium monohydrogenphosphate, sodium dihydrogenphosphate, various amino acids and the like and combinations thereof.
The isotonicity agent is subject to no particular limitation as long as it is water soluble and shows no adverse effect such as irritation to the eye and the like. For example, sodium chloride, potassium chloride, calcium chloride, glycerol and the like can be used.
As the surfactant, any of nonionic surfactant, anionic surfactant, amphoteric surfactant and cationic surfactant can be used. The surfactant is used as a sterilizing power improver and detergency improver.
Examples of the anionic surfactant include sodium lauroylsarcosinate, triethanolamine lauroyl-L-glutamate, sodium myristylsarcosinate and the like; examples of amphoteric surfactant include lauryldimethylaminoacetic betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolium betaine, alkyldiaminoglycine hydrochloride and the like; examples of nonionic surfactant include polysorbate 80, polyoxyethylene hydrogenated castor oil 60, polyoxyl 40 stearate, polyoxyethylene lauryl ether and the like; and examples of cationic surfactant include benzethonium chloride, benzalkonium chloride, cetylpyridinium chloride and the like.
Examples of chelating agent include sodium edetate, sodium citrate, sodium condensed phosphate and the like.
Examples of thickener include hydroxyethylcellulose, methylcellulose, polyvinyl alcohol, polyvinylpyrrolidone and the like.
Examples of wetting agent include glycerol, polyethylene glycol, propylene glycol and the like.
According to the present invention, the form of the agent for contact lenses is subject to no particular limitation as long as it can take a liquid form when in use. It may be a liquid, semi-solid agent or a solid agent that can be stored for a long time and dissolved when in use. Examples of the solid agent include tablet, granule, powder and lyophilized product. In view of rapid dissolution and the aspects of sterilization and homogeniety of the composition, a lyophilized product is preferable. These agents can be produced according to a conventional method.
The content and pH of the aforementioned oxo-acid compound and/or polyacid compound and other components in a semi-solid agent or solid agent are those that make the content and pH of a liquid agent prepared when in use fall within the above range.
The agent for contact lenses of the present invention can be used for any contact lens. It may be any of hard contact lens, oxygen permeable hard contact lens and soft contact lens.
When the agent for contact lenses of the present invention is used as a cleaning agent of contact lenses, a contact lens after use is placed in this cleaning solution and kept immersed therein for 1 to 12 hours. After cleaning, the lens can be worn without washing with water.